Optical recording apparatus, optical recording method, and digital still camera

ABSTRACT

A digital still camera includes a vibration detector for detecting vibrations. In accordance with certain conditions, a control unit controls finalization (session closing) which enables a CD-ROM drive to read data recorded on a recording medium. The control of session closing includes starting session closing after a predetermined period of time elapses since the selection of the execution of session closing. The countdown id displayed to indicate the time remaining before the start of session closing. After the countdown is completed, or when the vibration detector detects vibrations during the countdown until the start of session closing, session closing is not started.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to optical recording apparatuses, opticalrecording methods, and digital still cameras for recording data onrecording media by utilizing a laser beam, and more particularly relatesto an optical recording apparatus, an optical recording method, and adigital still camera for controlling a session closing in order toenable a reading apparatus to read data written in a recording medium.

2. Description of the Related Art

Disc recording media (hereinafter referred to as optical discs), such ascompact discs (CDs), which utilize optical mark reading have a largestorage capacity and can be accessed randomly. Since optical markreading is contactless, it does not involve risks such as head crashesand abrasion and damage caused by reading, compared with contact typerecording media, such as magnetic tapes. Because the surface of a discis robust, the risk of accidentally losing data is low. Accordingly,optical discs have many advantages and are suitable as computerperipheral memory and recording media in which data can be created andstored reliably.

Recently, read-write apparatuses which utilize a so-called CD-R (compactdisc-recordable), which is a write-once optical disc, have beendeveloped. Among CD-R's, there is one type of CD-R in which data iseasily written in accordance with all standard formats used in compactdiscs such as CD-ROM (compact disc read only memory), CD-ROM/XA (CD-ROMextended architecture), CD-I (compact disc interactive), and CD-DA(compact disc digital-audio). In place of conventional magnetic tapesand magnetic discs, CD-R's are installed in electronic apparatuses andare used as media from and/or to which data is read and/or written.

Since data to be recorded is written to a CD-R in an incremental manner,table of contents (TOC) information, which is recorded on the disc innerperimeter of a CD-ROM or the like, cannot be written when the CD-R isstill in a recordable state.

In other words, no finalization (session closing) is performed until itbecomes impossible to write any more data to the CD-R. Subsequently, theTOC information, which is index information for the recording medium, iswritten.

When no finalization is performed, that is, when the CD-R is in arecordable state, the start position for writing data and the recordedposition for reading data can be detected by referring to a provisionalTOC written in a program memory area (PMA) of the recording medium. ACD-ROM drive cannot read the provisional TOC written in the PMA, andhence it is impossible for the CD-ROM drive to read a write-oncerecording medium which is not finalized. In order to enable the CD-ROMdrive to read the write-once recording medium, it is necessary toperform finalization.

Referring to FIG. 12, a finalization process (session closing process)performed by a conventional recording apparatus is described.

In response to an instruction by the user to perform session closing, instep S41, the process reads information concerning written areasincluding provisional TOC information from a PMA of a recording medium.

In step S42, the process creates a normal TOC based on the informationon the written areas.

In step S43, the process embeds zero in a lead-out area.

In step S44, the process writes the normal TOC in a lead-in area. Whenthe writing is completed, the session closing is completed.

In session closing, a 23.5-Mbyte user data area is consumed by writingthe lead-in area and lead-out area according to the standard.

Concerning conventional recording apparatuses, finalization of awrite-once recording medium enables a CD-ROM drive to read thewrite-once recording medium.

When performing session closing in which session-closing data is writtento a recording medium, a regular single-speed recording apparatusrequires approximately 3 minutes and 40 seconds for closing a firstsession and approximately 1 minute and 30 seconds for closing second andsubsequent sessions.

When performing session closing, a conventional recording apparatus hasto record a large amount of data, especially when performing sessionclosing for the first time. It therefore requires a long period of timeto perform session closing.

A shock or vibration to the recording apparatus during session closingmay cause the recording apparatus to fail in session closing. When therecording apparatus fails in session closing, it is difficult for therecording apparatus to retry session closing. Due to a failure insession closing, it may become impossible to read data recorded on therecording medium.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anoptical recording apparatus, an optical recording method, and a digitalstill camera capable of preventing trouble which occurs in sessionclosing.

According to an aspect of the present invention, the foregoing objectsare achieved through provision of an optical recording apparatus forrecording data on a recording medium by optical recording, whichincludes a write unit for writing data to the recording medium. Acontrol unit controls session closing for enabling another readingapparatus to read the written data. The control unit performs sessionclosing in accordance with conditions for session closing.

The control unit may start session closing after a predetermined periodof time elapses since reception of a signal to perform session closing.The optical recording apparatus may further include a vibration detectorfor detecting vibrations. When the vibration detector detectsvibrations, the control unit may not start session closing. Therecording medium may include one of a write-once recording medium and arewritable recording medium.

According to another aspect of the present invention, the foregoingobjects are achieved through provision of an optical recording methodfor recording data on a recording medium by optical recording, whichincludes the steps of writing data to the recording medium andperforming session closing for enabling another reading apparatus toread the written data in accordance with conditions for session closing.

Session closing may not be started after a predetermined period of timeelapses since reception of a signal to perform session closing. Theoptical recording method may further include a vibration detecting stepof detecting vibrations. When vibrations are detected in the vibrationdetecting step, session closing may not be started. The recording mediummay include one of a write-once recording medium and a rewritablerecording medium.

According to another aspect of the present invention, the foregoingobjects are achieved through provision of a digital still camera whichincludes an image pickup unit for capturing an image of a subject. Animage processing unit processes the captured image data. A read-writeunit reads data from and/or writes data to a recording medium. A controlunit controls session closing for enabling a reading apparatus to readthe recorded data. The control unit performs session closing inaccordance with conditions for session closing.

The control unit may start session closing after a predetermined periodof time elapses since reception of a signal to perform session closing.The digital still camera may further include a vibration detector fordetecting vibrations. When the vibration detector detects vibrations,the control unit may not start session closing. The recording medium mayinclude one of a write-once recording medium and a rewritable recordingmedium.

According to the present invention, it is possible to prevent a sessionclosing failure which occurs during session closing or incompletesession closing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the structure of a unit (hereinafter referred to as avolume) on a removable recording medium for storing files and the likein a file system in compliance with a universal disc format (UDF);

FIG. 2 is a chart showing a file seeking process in the file system incompliance with the UDF;

FIG. 3 is a block diagram of the structure of a digital still cameraaccording to an embodiment of the present invention;

FIG. 4 is a sectional view, perpendicular to the surface of a recordingmedium, of the recording medium used in the digital still camera of theembodiment;

FIG. 5 is a sectional view, perpendicular to the surface of therecording medium, of the recording medium used in the digital stillcamera of the embodiment;

FIG. 6 illustrates the frame structure of absolute time in pregroove(ATIP) information written in a lead-in area of the recording mediumused in the digital still camera of the embodiment;

FIG. 7 is a diagram showing the intensity of an eight to fourteenmodulation (EFM) signal varying with time and the intensity of a radiofrequency (RF) signal when the EFM signal is written;

FIG. 8 illustrates the demodulation level of a pit used for computing anasymmetry value for each recording medium by the digital still camera ofthe embodiment;

FIG. 9 is a graph showing the relationship between the laser output forwriting data to the recording medium by the digital still camera of theembodiment and the asymmetry value after the data is written;

FIG. 10 is a graph showing the relationship between the asymmetry valuecomputed by the digital still camera of the embodiment when the writingis performed and a recording jitter value;

FIG. 11 is a flowchart showing a session closing process performed bythe digital still camera with respect to the recording medium; and

FIG. 12 is a flowchart showing a finalization process (session closingprocess) performed by a conventional recording apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will become apparent from the followingdescription of the preferred embodiment with reference to theaccompanying drawings.

A digital still camera according to an embodiment of the presentinvention writes captured image data to a write-once recording mediumand reads image data from the recording medium based on a file system incompliance with a universal disc format (UDF). The digital still cameracontrols finalization (session closing) for enabling another readingapparatus to read recorded image data in accordance with conditions.Specifically, the control of session closing includes starting sessionclosing after a predetermined period of time elapses since the executionof session closing is selected by a user and displaying the time untilsession closing is started. Also, when the user selects the execution ofsession closing, it is requested that the digital still camera should beplaced on a stable object. When a vibration detector detects vibrations,session closing is not started.

The digital still camera of the embodiment will now be described indetail.

The UDF is one definition for writing character codes of a file name andfile attributes which are available for various media such as a CD-R,WORM (write-once read-many optical disc), CD-R/RW (compactdisc-recordable/rewritable), MO (magneto-optical disc), and DVD (digitalversatile disc). The UDF is endorsed by the Optical Storage TechnologyAssociation (OSTA).

In other words, the UDF is a system in which data can be written by anyoperating system (OS) and written files can be compatibly read by anyOS.

In the UDF, a file entry information control block (ICB) is used as themain data structure. In the UDF, all files and directories have a uniqueICB. In this embodiment, a file which stores actual data such as imagedata for a captured image is generally written prior to the ICB whichdefines the file. When a file is stored in a plurality of extents (datastreams), a list of extents is included in the ICB.

In the UDF, a mapping table which is referred to as a virtual allocationtable (VAT) is used to allocate a sequential number (virtual address) toeach file so that it is possible to make a virtual reference. In a filesystem in compliance with the international standard ISO 9660, each fileor each directory on a recording medium is directly referred to by alogical address. In contrast, in the UDF, each file or each directory isreferred to by the above-described virtual address. The VAT can beplaced at any position on a track, and the VAT can be referred to by aVAT ICB which indicates the position of the VAT.

In the UDF, it is defined that the VAT ICB is placed at a last-recordedphysical address on the recording medium. Although the VAT is dividedand placed on a plurality of extents, the VAT ICB includes a VAT extentlist. In the UDF, when a file is modified in one way or another, it isnot necessary to change the entirety of a series of file pointers. It isnecessary to only change the VAT ICB in order to arrive at the changedfile.

FIG. 1 shows the structure of a unit (hereinafter referred to as avolume) on a removable recording medium which stores files and the likein a file system in compliance with the UDF.

In the file system in compliance with the UDF, it is assumed that thehead of a session is sector 0. Between a beginning extended areadescriptor (BEAD) recorded in sectors from sector 16 onward and aterminating extended area descriptor (TEAD), a volume structuredescriptor (VSD) is placed. In the VSD, information for recognizing theUDF file system is written.

In the file system in compliance with the UDF, when the recording mediumis in a state in which data is still writable thereto and a session isnot closed yet, recording of an anchor volume descriptor pointer (AVDP)at which an optical head first reads data in order to arrive at a fileis authorized. If the head of the session is sector 0, the AVDP iswritten in a sector having a logical block number (LBN) of 512.

In other words, when the AVDP is stored in sector 512, it can beconcluded that the data is written based on the file system incompliance with the UDF. By performing session closing of the recordingmedium, the AVDP is written in two sectors, i.e., LBN=sector 256 andLBN=(LBN of last written sector)−256. After session closing isperformed, the ADVP written in sector 512 is not used when reading data.The AVDP indicates a volume descriptor sequence (VDS). The VDS iswritten on sectors from sector 512 onward.

The VDS is a set of descriptors indicating information concerning thecontents of the volume structure. The VDS includes volume informationand partition information such as a primary volume descriptor, a logicalvolume descriptor (hereinafter referred to as an LVD), an applicationvolume descriptor, a virtual partition descriptor, and an actualpartition descriptor.

There are two types of partitions. One is an actual partition, and theother is a virtual partition. The actual partition includes the actuallogical address of data recorded on the recording medium. In contrast,the virtual partition includes a table based on the virtual address ofdata. In other words, the virtual partition is a partition obtained byremapping the entire recording area of the recording medium from thephysical address to the virtual address. The virtual partition isdefined by the VAT.

In the VDS, two descriptors indicating the actual partition and thevirtual partition are placed. When the partition number is zero, thefile system refers to the actual partition, that is, to the actuallogical address. When the partition number is one, the file systemrefers to the virtual partition (VAT).

The LVD in the VDS is a file set descriptor sequence (FSDS), that is, aset of file sets in the volume. Each FSDS indicates a root directoryinformation control block (RDICB). The RDICB includes information suchas a specific directory name, file name, and the like.

In the file system in compliance with the UDF which is suitable forpacket writing, there are two schemas. One schema is a file entry ICBfor identifying each file in the file system, and the other schema is afile identifier descriptor (FID). The FID indicates the physical addressof the file entry ICB or indirectly indicates the file entry ICB throughthe VAT.

A directory which is referred to by the RDICB is configured as a tableof related FIDs. The file entry ICB includes extent lists for all storedfiles, dates, and file attributes. The contents of the file entry ICBare physical addresses which may be changed when files are modified oredited.

The FID indicates the file entry ICB. A file entry which is referred toby the file entry ICB indicates the actual file. Since a directory isone type of file, the file entry can indicate the directory. In the filesystem in compliance with the UDF, a tree-shaped hierarchical structureis formed.

A root directory can be referred to by the RDICB. The root directoryincludes an FID for referring to a file entry ICB or an FID forindicating a directory entry ICB.

For example, the FID has information such as “partition 1/block 200”. Ifthe partition number is one, it is a virtual partition. Hence, the filesystem does not directly go to the logical address #200 in order to finda file. Instead, the file system refers to the VAT, and the VAT in turnindicates the logical address.

With the above-described file system, the UDF performs a file seekingprocess shown in FIG. 2.

An optical head reads the last area from among written areas on a disc.In this area, the VAT ICB is written. Based on the VAT ICB, the VAT isread.

The optical head refers to the AVDP. Subsequently, the optical headrefers to the VDS written in the AVDP.

Based on the VDS, it is determined whether the partition is an actualpartition or a virtual partition.

Also, the FSDS is referred to by the VDS. In the FSDS, the RDICB isindicated. In the RDICB, the root directory is indicated. In the rootdirectory, the FID indicates the ID of each file.

When the partition flag in the VDS in the root directory formed of theFID indicates an actual partition, direct reference to the physicaladdress of the file entry ICB is made. In contrast, when the flagindicates a virtual partition, reference to the file entry ICB is madethrough the VAT. As a result, the file seeking process arrives at adesired file.

Provision of the VAT between the FID and the file entry ICB ensuresthat, even when the file entry ICB is rewritten, the file entry ICB isvirtually rewritten by changing the address of the file entry ICB on theVAT.

Even when the location of the file entry ICB is changed by changing thecontents of the root director, it is not necessary to rewrite the FIDwhen the VAT is changed.

In the file system in compliance with the UDF, the above-describedseeking process enables a sequentially writable recording medium to behandled as if it were a random access read-write recording medium.

Referring to FIG. 3, the structure of the digital still camera of theembodiment is described. For example, the digital still camera readsdata from and writes data to a recording medium. In this embodiment, aso-called disc-shaped CD-R is used as a write-once recording medium.

A digital still camera 1 includes an image pickup unit 10 for capturingan image of a subject; an image signal processor 11 for converting animage signal from the image pickup unit 10; a display unit 12 fordisplaying operating information for operating the digital still camera1 and the image signal; an optical pickup (OP) 13 for reading data fromand/or writing data to a recording medium (which will be describedbelow); a radio frequency (RF) processor 14 for RF-processing the readsignal; a servo signal processor 15 for generating a servo signal basedon each signal from the RF processor 14; an analog filter processor 16for generating an analog signal for controlling each driver based on thesignal from the servo signal processor 15; a signal processor 17 forprocessing the read signal from the recording medium; a spindle driver18 for controlling the rotation of a spindle motor 22; a sled driver 19for controlling the operation of a sled motor 23; a tracking driver 20for rocking an objective lens in the OP 13; a focus driver 21 forcontrolling the focus of a beam by vertically moving the objective lensin the OP 13 with respect to the disc recording medium; the spindlemotor 22 for driving the disc recording medium; the sled motor 23 formoving the OP 13 in the radial direction of the recording medium; avibration detector 24 for detecting vibrations; and a control unit 25for controlling each part. The digital camera 1 writes captured imagedata to a recording medium 26 and reads image data from the recordingmedium 26.

The image pickup unit 10 includes a lens 30 for capturing an image of asubject; a charge coupled device (CCD) 31 for generating an imagesignal; a sampling/holding (S/H) circuit 32; and an A/D convertingcircuit 33 for converting an image signal into a digital signal. The CCD31 generates an image signal based on an image of a subject from thelens 30 and supplies the generated image signal to the S/H circuit 32.The S/H circuit 32 samples and holds the image signal from the CCD 31and supplies the image signal to the A/D converting circuit 33. The A/Dconverting circuit 33 converts the image signal from the S/H circuit 32into a digital signal and supplies the digital signal to the imagesignal processor 11.

Under the control of a central processing unit (CPU), the image signalprocessor 11 performs image processing of the digital signal from theimage pickup unit 10. Specifically, the image signal processor 11performs color conversion from RGB signals into color-difference andchrominance signals, white balance processing, γ correction, reducedimage processing, JPEG compression, and the like. The processed imagesignal is supplied to the signal processor 17. The image signalprocessor 11 supplies the processed image signal to the display unit 12.

The display unit 12 is, for example, a liquid crystal display (LCD), anddisplays the image signal from the image signal processor 11.

The OP 13 includes the objective lens, a laser diode (LD), a laser diodedriver, a photodetector IC, a half mirror, and the like. The OP 13detects an optical signal and outputs the optical signal to the RFprocessor 14. The OP 13 writes data to the recording medium 26 based ona decoded eight to fourteen modulation for write (DECEFMW) signal outputfrom the signal processor 17 for flashing and driving the laser, anoptimum power control (OPC) signal (write strategy) indicating theoptimum value of the laser intensity, and the like.

The RF processor 14 samples and holds eight system signals consisting ofa beam signal, side, and main, and performs arithmetic processing togenerate signals such as a focus error (FE) signal, a tracking error(TE) signal, a mirror (MIRR) signal, an absolute time in pregroove(ATIP) signal, and a main read signal based on predetermined signalsfrom among the eight system signals. From among the generated signals,the RF processor 14 outputs frequency modulation data (FMDT), afrequency modulation clock (FMCK), TE, and FE to the servo signalprocessor 15. The RF processor 14 outputs the OPC signal indicating theoptimum value of the laser intensity and the DECEFMW signal for flashingand driving the laser, which are detected by test writing, to the signalprocessor 17. The RF processor 14 outputs MIRR to the control unit 25.

The servo signal processor 15 receives the FMDT, FMCK, TE, and FE fromthe RF processor 14. Under the control of the control unit 25, the servosignal processor 15 generates signals for controlling various servosinherent in optical discs and outputs the signals to the analog filterprocessor 16.

The analog filter processor 16 generates analog signals based on thecontrol signals for various servos, which are output from the servosignal processor 15, and outputs the analog signals to the spindledriver 18, the sled driver 19, the tracking driver 20, and the focusdriver 21.

Under the control of the control unit 25, the signal processor 17receives the OPC and DECEFMW from the RF processor 14 and performsprocessing such as cross interleaved Reed-Solomon code (CIRC) decodingand encoding, write strategy, ADDr decoding, asymmetry computation,running optimum power control (OPC), and the like. When writing data tothe recording medium 26, the signal processor 17 outputs the DECEFMWsignal for flashing and driving the laser, the OPC signal indicating theoptimum value of the laser intensity, and the like to the OP 13.

Based on the signal from the analog filter processor 16, the spindledriver 18 controls the rotation of the spindle motor 22.

Based on the signal from the analog filter processor 16, the sled driver19 controls the sledding movement of the sled motor 23.

Based on the signal from the analog filter processor 16, the trackingdriver 20 rocks the OP 13 and controls the position of a beamirradiation spot on the disc surface of the recording medium 26.

Based on the signal from the analog filter processor 16, the focusdriver 21 moves the OP 13 vertically with respect to the disc surface ofthe recording medium 26, thereby performing focus control of the laser.

Based on the signal from the spindle driver 18, the spindle motor 22rotates the recording medium 26.

Based on the signal from the sled driver 19, the sled motor 23 causesthe OP 13 to sled.

The control unit 25 includes a program memory for storing a program forperforming various processes, a static random access memory (SRAM) as awork area for temporarily storing VAT ICB and various data, and the CPU.The control unit 25 controls reading and writing of VAT ICB. The controlunit 25 controls the overall apparatus by controlling each part.

Specifically, the SRAM is used as a work area for temporarily developingthe VAT ICB fetched from the recording medium 26. A dynamic randomaccess memory (DRAM) stores a correspondence table indicating therelationship between the VAT, which is updated every time a file or adirectory is updated, added, or deleted, and logical addresses on therecording medium 26 on which the virtual partition begins. The DRAMstores the correspondence table until the main power supply of thedigital still camera 1 is turned off.

The recording medium 26 is a write-once recording medium in which datais read and written based on the file system in compliance with the UDF.Specifically, the recording medium 26 has a disc shape and is aso-called CD-R.

FIGS. 4 and 5 show cross sections of the recording medium 26. FIG. 4 isa vertical sectional view of the recording medium 26 with respect to thedisc surface. FIG. 5 shows an enlarged view of the inner perimeter sideof the sectional view shown in FIG. 4.

Referring to FIG. 4, the recording medium 26 includes a powercalibration area (PCA), a program memory area (PMA), a lead-in area, andan information area.

Referring to FIG. 5, the power calibration area includes a test area foractually performing test writing and a count area for counting the startposition of test writing and the number of times test writing isperformed.

In FIGS. 4 and 5, shaded portions indicate written areas.

The test area is divided into 100 partitions. Each partition isdesignated by relative time from the start time of the lead-in area.Each partition consists of a minimum of one frame. Each partition isdivided into five sub-partitions. One sub-partition is divided intothree frames. Hence, each partition consists of a maximum of 15 frames.By utilizing the sub-partitions, test writing is performed immediatelybefore writing, and hence the laser output is adjusted.

The operation of each component of the digital still camera 1 with theabove arrangement for reading a signal recorded on the recording medium26 will now be described.

A lens optical system in the OP 13 reads the laser diode light, which isreflected from the disc surface of the recording medium 26. Light fromthe lens optical system is converted by the photodetector IC (PDIC) intoan electrical signal, and the electrical signal is sampled and held inthe RF processor 14. Based on eight predetermined signals, signals suchas FE, TE, MIRR, ATIP, and the main read signal are generated byarithmetic processing.

Characteristics of FE obtained by the RF processor 14 are adjusted bythe servo signal processor 15, and FE passes through the analog filterprocessor 16 and is input to the focus driver 21. The focus driver 21vertically moves a lens driving focus coil (not shown) in the OP 13 andadjusts the focus.

Similarly, the AC component of TE obtained by the RF processor 14 isremoved by the servo signal processor 15, and TE undergoes digitalprocessing. Subsequently, TE passes through the analog filter processor16 and is input to the tracking driver 20. The tracking driver 20adjusts a lens driving tracking coil in the OP 13 in the radialdirection and adjusts the tracking.

Also, the DC component of TE obtained by the RF processor 14 is removedby the servo signal processor 15, and TE undergoes digital processing.Subsequently, TE passes through the analog filter processor 16 and isinput to the sled driver 19. The sled driver 19 activates the sled motor23 and moves the overall OP 13 in the radial direction of the recordingmedium 26 and adjusts the sledding movement. During the seek operation,the voltage for performing the sled control is intentionally appliedfrom the outside. As a result, the sled motor 23 is forcedly driven.

Accordingly, the tracking operation for adjusting only the lens in theradial direction is performed based on the AC component of TE, and thesled operation for moving the overall OP 13 in the radial direction isperformed based on the DC component of TE.

The detecting signal (MIRR) which indicates a variation in thereflectivity of the recording medium 26, which is output from the RFprocessor 14, is detected when the OP 13 crosses a track. By countingMIRRs, the CPU can detect the current seek position and the current readposition and can start and stop the optical pickup operation.

The spindle motor 22 is controlled based on ATIP processing. In a spiralgroove referred to as a wobbling groove, which is written on therecording medium 26, time information is recorded by performingfrequency modulation at a center frequency of 22.05 kHz±1 kHz in theradial direction. In this frequency modulation, time informationreferred to as ATIP, which is Bi-phase-modulated, is modulated.

When the focus and the tracking are in concordance with each other, awobble signal is generated based on a predetermined combination of eightinput signals. The wobble signal undergoes frequency modulation and ATIPdecoding, and a clock signal (FMCK) which corresponds to the centerfrequency and time information (FMDT) are generated.

The FMDT is classified as media absolute time position by the servosignal processor 15, that is, it is classified as address and additionalinformation, and is stored in a predetermined register. Accordingly, theCPU performs reading via a bus.

In the read operation, the RF processor 14 generates a signal whichcorresponds to a recording pit, based on a predetermined combination ofthe eight signals. The generated signal undergoes equalization and issupplied to the signal processor 17 in which the signal remains in theEFM signal format. The signal processor 17 performs CIRC decoding andobtains the desired data.

The write operation will now be described. In the write operation, apickup is moved to the lead-in area, and ATIP information is read. Fromamong the ATIP information, special information 2 is read.

FIG. 6 shows the frame structure of the ATIP written in the lead-inarea. In a frame with the frame number N, special information 1 iswritten. In a frame with the frame number (N+10), special information 2is written. In frames with the frame numbers (N+1) to (N+9) subsequentto special information 1 and in frames with the frame numbers (N+11) to(N+19) subsequent to special information 2, normal time codes arewritten.

In each special information area which is written every ten frames, thestart position of the lead-in area of the recording medium 26 is writtenas time information. In special information 2 area with the frame number(N+10), which is to be read in this example, the start position of thelead-in area is written as time information in a predetermined format.

For example, when the lead-in area starts at a position at which 2minutes and 11 seconds have elapsed since the recording start point ofthe recording medium 26, a digital signal of time information indicating97 minutes and 49 seconds, which is obtained by subtracting 2 minutesand 11 seconds from total recording time of 100 minutes, is written inthe special information 2 area of the recording medium 26. In otherwords, time information “97:49:00” is written as “1001 0111 0100 10010000 0000”.

The information written in the special information area corresponds toan identification code for identifying a recording medium. Arecording-medium reading apparatus stores in advance a table indicatingthe relationship between a write strategy parameter which corresponds tothe identification code and other related parameters. A write strategyis a correction parameter for adjusting the duration and level of awrite laser pulse for each pit so that the pit size after the writing isin accordance with the standard. The reading apparatus is provided inadvance with a write strategy for each recording medium. Referring toFIG. 7, a recording signal in accordance with the write strategy isdescribed in detail.

FIG. 7 shows an EFM signal A and an actual RF write signal B for writingthe EFM signal A. The RF write signal B in accordance with the writestrategy starts writing after a delay aT. In the initial writing period(bT), writing is performed with an output which is larger than Pw by ΔP.Subsequently, writing is performed with the output Pw.

Next, the optimum power calibration (OPC) operation for determining theoptimum value of the laser output is performed. While theabove-described write strategy is precise control of the laser for eachpit, the OPC operation computes the optimum value of the laser outputfor the overall write operation. The OPC operation is performed in orderto obtain a pit writing preset value for achieving a desired value forideal reading.

The OPC operation is performed in the test area of the PCA. The testarea is divided into 100 partitions, and each partition is designated byrelative time from the start position of the lead-in area. Eachpartition is divided into a maximum of fifteen frames. By using onepartition, test writing is performed prior to performing the actualwriting. Hence, the laser output can be adjusted.

Specifically, the laser output is changed in a stepwise manner startingfrom a predetermined value, and writing to the recording medium 26 isperformed step by step. The laser output is read, and an asymmetry valueat each step is measured. Linear approximation is performed using apreset value in the vicinity of a desired asymmetry, and hence a presetvalue of the laser output which indicates the desired asymmetry value isobtained.

An asymmetry value is a value which defines a gap between the centerlevel of 3T pit/land and the center level of 11T pit/land. The asymmetryvalue is computed by the following equation (1). FIG. 8 shows thedemodulation level used to compute the asymmetry value.asymmetry value (%)=(3T center−11T center)/11T amplitude . . .  (1)

A desired asymmetry value is an ideal value which minimizes the jittervalue. The asymmetry value is included in write strategy parameters as avalue inherent in the recording medium 26. The asymmetry valuecorresponds to the start position information of the lead-in area of therecording medium 26 and is stored beforehand. In this example, thedesired asymmetry value is set to −5%.

FIG. 9 shows the relationship between the laser output when writing isperformed and the asymmetry value after writing is performed. As isclear from FIG. 9, the laser output when writing is performed isproportional to the asymmetry value after writing is performed. Ingeneral, the laser diode used as the optical pickup for CD-R has a largevariation in laser output relative to the operating environmentaltemperature. When the laser output is preset so that it achieves thedesired asymmetry value at room temperature, as shown in FIG. 9, thelaser output varies greatly with the environmental temperature. As aresult, as is clear from a graph in FIG. 10 which shows the relationshipbetween the asymmetry value and the recording jitter value, variation inthe asymmetry value influences a deterioration of the recording jittervalue.

It is therefore necessary to perform the OPC operation which determinesthe optimum value of the laser output immediately before the writeoperation. After the optimum setting of the laser output is performed inaccordance with the foregoing procedure, each parameter which isprepared as a fixed value is set, and hence the optimum writing isimplemented. The asymmetry value is obtained by an A/D converter and ismeasured by the signal processor 17.

In the count area of the PCA, when the OPC operation is performed, ifany one of the sub-partitions in each partition is used, a correspondingpartition in the count area becomes filled. When performing the OPCoperation later, unused sub-partitions in a used-partition of the PCAare sought for prior to performing the OPC operation.

Specifically, the write operation is performed as follows. The signalprocessor 17 performs CIRC encoding and EFM encoding of compressedcaptured image data in the SRAM, and outputs the DECEFMW signal forflashing and driving the laser, which is required for pit formation, andthe OPC (write strategy) signal which indicates the optimum value of thelaser intensity to the laser diode driver in the OP 13.

Writing is performed with predetermined timing in accordance with a filesystem based on an address in frame which is obtained based on the FMDTsignal obtained by decoding the ATIP.

In the initial writing, writing starts at a position after a gap ofapproximately 20 Mbytes, which is to be used as the lead-in area whensession closing is performed later.

When writing of additional data is not performed to a write-oncerecording medium, or when reading the recording medium using anotherreading apparatus such as a CD-ROM drive, it is necessary to performfinalization (session closing) in which the lead-in area and thelead-out area are written, in order to enable the CD-ROM drive to readthe recording medium.

In this embodiment, the finalization process (session closing) iscontrolled in accordance with certain conditions. Specifically, thecontrol of session closing includes starting session closing after apredetermined period of time elapses since the execution of sessionclosing is selected by a user and displaying of the time remainingbefore the start of session closing. Also, when the user selects theexecution of session closing after the countdown is completed, it isrequested that the digital still camera should be placed on a stableobject. When the vibration detector detects vibrations, session closingis not started.

More specifically, when the execution of session closing is selected,the digital still camera 1 displays that it should be situated in astable place. After the digital still camera 1 is securely placed, theuser is notified to press a confirmation button.

The duration between the selection of the execution of session closingand the start of session closing is, for example, five seconds. When theconfirmation button is pressed, the countdown begins.

When vibrations are detected by the vibration detector during thecountdown, the countdown to session closing is stopped.

FIG. 11 shows a process of performing a session closing process by thedigital still camera 1 of the embodiment.

When a user selects the execution of session closing, in step S1, thecontrol unit 25 reads a provisional TOC written in the PMA of therecording medium 26.

In step S2, the control unit 25 creates a normal TOC based on theprovisional TOC.

In step S3, the control unit 25 displays a warning to place the digitalstill camera 1 in a stable place and to confirm that it is ready toperform session closing. For example, the warning “Please place thecamera in a stable place. If it is ready, please press the confirmationbutton” is displayed.

In step S4, the control unit 25 determines whether the confirmationbutton is pressed. If it is determined that the confirmation button ispressed, in step S5, the control unit 25 displays the countdownindicating the time remaining before the start of session closing. Forexample, the countdown “5→4→3→2→1→ session is being closed” isdisplayed.

In contrast, if the process cannot determine in step S4 that theconfirmation button is pressed, the process repeats step S4.

During the countdown, when the vibration detector detects vibrations,the process performs processing which prohibits the digital still camera1 from performing session closing. For example, the process is repeatedfrom step S3 or the digital still camera 1 is disabled from performingsession closing. As a result, failures in session closing are prevented.

When no vibrations are detected, the countdown is properly completed. Instep S6, the process starts session closing. When session closing isstarted, the control unit 25 first writes to a lead-out area.Specifically, the control unit 25 writes information so that zero isembedded in the lead-out area.

When the writing to the lead-out area is completed, in step S7, theprocess writes to a lead-in area. Specifically, the process repeatedlywrites the normal TOC created in step S2.

When the writing to the lead-in area is completed, the control unit 25displays in step S8 that session closing is completed, and the processis terminated. For example, the message “session closing is completed”is displayed.

According to the digital still camera 1 of the embodiment of the presentinvention, when the execution of session closing is instructed, sessionclosing is started after a predetermined period of time. A user isinstructed to place the digital still camera 1 in a secure place. Whenthe vibration detector detects vibrations, session closing is notperformed. It is thus possible to prevent the occurrence of trouble suchas failure in session closing and incomplete session closing.

While the present invention has been described with reference to whatare presently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiment. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. An optical recording apparatus for recording data on a recordingmedium by optical recording, comprising: write means for writing data tosaid recording medium; and control means for controlling session closingfor enabling another reading apparatus to read the written data; whereinsaid control means performs session closing in accordance withconditions for session closing; and said control means starts sessionclosing after a predetermined period of time elapses since reception ofa signal to perform session closing.
 2. An optical recording apparatusaccording to claim 1, wherein said control means displays the remainingtime from the reception of the signal to perform session closing untilthe start of session closing.
 3. An optical recording apparatusaccording to claim 1, wherein said control means confirms, after thepredetermined period of time elapses since the reception of the signalto perform session closing, whether to perform session closing.
 4. Anoptical recording apparatus according to claim 1, wherein said controlmeans gives, after the reception of the signal to perform sessionclosing, a warning to put said optical recording apparatus on a steadyobject.
 5. An optical recording apparatus according to claim 1, furthercomprising vibration detecting means for detecting vibrations, whereinsaid control means does not start session closing when said vibrationdetecting means detects vibrations.
 6. An optical recording apparatusaccording to claim 1, wherein said recording medium comprises one of awrite-once recording medium and a rewritable recording medium.
 7. Anoptical recording apparatus according to claim 5, wherein said controlmeans starts session closing after a predetermined period of timeelapses since reception of a signal to perform session closing.
 8. Anoptical recording apparatus according to claim 7, wherein said controlmeans displays the remaining time from the reception of the signal toperform session closing until the execution of session closing.
 9. Anoptical recording apparatus according to claim 7, wherein said controlmeans does not start session closing when said vibration detecting meansdetects vibrations within the predetermined period of time from thereception of the signal to perform session closing.
 10. An opticalrecording method for recording data on a recording medium by opticalrecording, comprising the steps of: writing data to said recordingmedium; and performing session closing for enabling another readingapparatus to read the written data in accordance with conditions forsession closings, wherein session closing is started after apredetermined period of time elapses since reception of a signal toperform session closing.
 11. An optical recording method according toclaim 10, wherein the remaining time from the reception of the signal toperform session closing until the start of session closing is displayed.12. An optical recording method according to claim 10, wherein, afterthe predetermined period of time elapses since the reception of thesignal to perform session closing, it is confirmed whether to performsession closing.
 13. An optical recording method according to claim 10,wherein, after the reception of the signal to perform session closing, awarning is given to put said optical recording apparatus on a steadyobject.
 14. An optical recording method according to claim 10, furthercomprising a vibration detecting step of detecting vibrations, wherein,when vibrations are detected in said vibration detecting step, sessionclosing is not started.
 15. An optical recording method according toclaim 10, wherein said recording medium comprises one of a write-oncerecording medium and a rewritable recording medium.
 16. An opticalrecording method according to claim 14, wherein session closing isstarted after a predetermined period of time elapses since reception ofa signal to perform session closing.
 17. An optical recording methodaccording to claim 16, wherein the remaining time from the reception ofthe signal to perform session closing until the execution of sessionclosing is displayed.
 18. An optical recording method according to claim16, wherein session closing is not started when vibrations are detected,in said vibration detecting step, within the predetermined period oftime from the reception of the signal to perform session closing.
 19. Adigital still camera, comprising: image pickup means for capturing animage of a subject; image processing means for processing the capturedimage data; read-write means for reading data from and/or writing datato a recording medium; and control means for controlling session closingfor enabling a reading apparatus to read the recorded data, wherein saidcontrol means performs session closing in accordance with conditions forsession closing; and said control means starts session closing after apredetermined period of time elapses since reception of a signal toperform session closing.
 20. A digital still camera according to claim19, wherein said control means displays the remaining time from thereception of the signal to perform session closing until the start ofsession closing.
 21. A digital still camera according to claim 19,wherein said control means confirms, after the predetermined period oftime elapses since the reception of the signal to perform sessionclosing, whether to perform session closing.
 22. A digital still cameraaccording to claim 19, wherein said control means gives, after thereception of the signal to perform session closing, a warning to putsaid optical recording apparatus on a steady object.
 23. A digital stillcamera according to claim 19, further comprising vibration detectingmeans for detecting vibrations, wherein said control means does notstart session closing when said vibration detecting means detectsvibrations.
 24. A digital still camera according to claim 23, whereinsaid control means starts session closing after a predetermined periodof time elapses since reception of a signal to perform session closing.25. A digital still camera according to claim 24, wherein said controlmeans displays the remaining time from the reception of the signal toperform session closing until the execution of session closing.
 26. Adigital still camera according to claim 24, wherein said control meansdoes not start session closing when said vibration detecting meansdetects vibrations within the predetermined period of time from thereception of the signal to perform session closing.
 27. A digital stillcamera according to claim 24, wherein said recording medium comprisesone of a write-once recording medium and a rewritable recording medium.